I disagree, if the tree is energized there will be sparking/action at the contact point to warn an observant person on the ground. You're splitting hairs to say it would be safer to be on rope than on the ground touching an energized tree. Anyone care to test the theory?

My point is that a REC climber is causing a safety/danger escalation if they climb a tree with wires close to or through the crown. The climb may be completely uneventful but things happen. As a kid I free climbed a conifer many times that had power lines contacting the trunk in the crown. I climbed very close to the lines, just didn't touch them. as a semi-rational adult you can get away with it but why bother? Just go find a tree that doesn't have powerlines.

Here's an analogy: A tourist visits an African safari style park. Rules are don't get out of the tour vehicle. It's not actually dangerous to get out of the vehicle. chances are nothing would ever happen, the animals in this park have been conditioned by the park staff to keep distance from the vehicles. Okay, the park has a perfect 10 year safety record, then one day a tour participant decides they must take a leak in the bushes, then they take an unexpected cell call. They've now made two mistakes, they're in the wrong place and they're distracted, a lion sneaks up and grabs them by the head, end of story.

In the scenario there is no direct danger to getting out of the tourist bus and standing on the ground, but the tourist is putting themselves in a position to make a mistake that could indeed be dangerous. Stay on the bus and the opportunity to make a mistake is removed.
-Andrew

Well, I disagree with you. First, I nor no one else said anything about a tree in contact with a line; nobody said anything about an energized tree. Why would it even be necessary to ask it we should climb an energized tree, or a tree in contact with lines? That was never the issue. The question all along has been how close, not if it's in contact with the tree and not if the power line is in the tree. Nobody but you has mentioned anything about a condition where the tree is sparking, burning, arcing, or anything of the sort. You know moss we do have a little sense.


Again moss, nobody is talking about climbing a tree with power lines above it or through it. The subject is how much distance the tree needs to be from a power line to be safe. No one but you was addressing if it would be safe to climb in a tree if the climb takes you closer and closer to the power lines.


Again, nobody is talking about trees with power lines in them or touching them. How dumb do you think we are? Are you off your meds today or something?

This is what I like about this forum. I ask a question and I get all sorts of feedback, all of which is good. I like it when a lot of discussion comes out of an issue. It provides much food for thought.

My thought: I believe I like the idea of staying away from a tree that is closer to a power line than the height of the tree. I see jmaher's rule of thumb as the best advice to be found in this discussion.

Let me clarify, if a tree is dangerous to touch when a person is on the ground it's defacto energized. If current isn't running through the tree it isn't dangerous to touch, right?

Ok, let's say the tree isn't energized but is close to a power line. A person touches the tree, nothing happens. Ok, now the person climbs the tree. They're employing a rope, they've increased their risk over the person standing on the ground. Why? Because they are moving about the tree and could accidentally cause a part of the tree (by weighting an upward angled flexible branch for example) or their body or their gear to contact the wire. This is why I disagree with your point that it's more hazardous to touch a tree near a wire than it is to climb a tree near a wire.
-Andrew

Look at Tom's post. Two cylinders, one around the tree, and the other cylinder around the line. As Tom stated it, those cylinders must be 10 feet apart. There can be no limbs and lines overlapping to pose a potential problem due to climbing the tree. If there is, then the tree doesn't meet the distance requirement.

This is pretty simple stuff moss. Nobody is dumb enough to climb a tree that has limbs so close to a hv power line that they could make a limb come in contact with the line by climbing in the tree. Nobody is dumb enough to climb a tree with power lines running through it, or in contact with the tree. Well, you have it seems. If the tree doesn't make the safe distance rule under all circumstances, and Tom offered some good guidelines used by professionals, then it's a danger tree.

Sounds good Ron, I was just disagreeing with the part that a tree dangerous to climb (because of wires) is more dangerous to a person on the ground than a climber, I read the entire thread and understand all the concepts.

I believe the ten foot rule is a work climbing guideline, for example the GOTC program climb guideline (facilitated rec climb) says 20 ft. (I think, could be more than that).
-Andrew

I do climb a tree in my backyard that is right next to and below two power lines plus TV cable lines.

The down service line to my house is actually two cables (insulated wrapped together in a bundle plus the ground wire that is exposed.) I have cleaned branches near or close to that one line and I am fairly safe while trimming stuff around there.

Now Above and in top of the corner pole is the 250volt (I don't know the capacity of the three primary lines (10 to 15KW)but it is strong enough to handle the entire line of houses down the street and every two or three poles there is a transformer so that one is above my tree and I try to stay the heck away from those lines BUT ( there is always a BUT) once I send the throw line over two of those lines and I was very concerned about retrieving that line - No indication of any of burning or sparking but I am sure that the potential for electrocution was there present under the right moisture and conductivity of the material and from experience growing up with my family owning an electrical power plant where we could see how much damage a live wire can do in milliseconds - It does not take much time to kill a person or at least give it a good burn.

So, I am fairly careful every time I climb there to make sure no branches have grown into the lines since the last climb and that I call the line maintenance crews if I see something that is uncomfortable to me. Touching the tree is not likely to cause a problem but you never know.

Like Tom said: Electricity and Gravity are always working!

Rules are great, and everybody needs to be reminded of them from time to time -- but common sense has probably saved more lives than any set of rules/regulations.

Or, as Momma Gump told Forest Gump: "Stupid is as stupid does...!"

Exactly! Now where did I put that Home Depot rope? I think I want to go out and climb next to that powerline!

YeeHa! (can you tell I'm bored?)
-Andrew

Well, rules aren't everything, but they are a large and important part of safety. We live in a society that basically imposes rules, often very strictly enforced rules for our protection, especially in professional work with risk to it. We even have laws - seat belts, and regulations in shops etc, eye & ear protection, safety lines, helmets on construction sites etc.

Rules, if we obey them, basically protect us from dangers we may not be aware of or fully understand. Rules can't totally eliminate accidents, but the sure do reduce the risks. Common sense can only be applied if we fully understand all the dangers and ramifications involved in a situation. The rules come from common sense from those with experience and knowledge of their field of expertise, where our common sense may not have that strong of a backing.

There can easily be unforeseen elements that our common sense would not be taking into account. This is especially true when it comes to electricity. Having worked as an electrical engineer for a power generating company, TVA, I've had some enlightenment as to what high voltages can do and it's not always what we'd expect.

I've taught MANY Electrical Hazard Awareness Program sessions. In some of the classes I've had the good fortune of having journeyman lineman in the class. These are the people who BUILD and maintain the transmission lines. I've asked them, the experts, what they think of the mythical 'clean, dry rope'. If a comrade of theirs was in contact with an energized line, would they use a rope to break contact? Never has one of them said anything but a definitive NO...no hesitation in their reply either. The look on their face is always the same look the tells me that the question is stooopid too.

Sure, the rope materials are non-conductive but are they insulators?

The ten foot tubes are what OSHA has set as the work standard. sure, we all know of examples of trees that violate the approach distance. But...why tempt fate?

No offense at all to linemen, but actually linemen are essentially mechanics, although I'm sure they have been taught guidlines about electricity. But if I were to ask a lineman which had the greater dielectric strength, dry air or dry polyester, they wouldn't have a clue what I was talking about.

Yes, a non-conductor is an insulator. That's what an insulator is - a material that doesn't conduct electricity. Better still an insulator is quantified by its dielectric strength. 3M offers polyester tape as a high dielectric insulator. The higher the dielectric, the higher the voltage it can withstand. For example, the tape is 2.2 mils (that's 0.0022 inchis or two-thousandths of an inch thick) and that thickness breaks down at 5000 volts. So how much would it take to withstand 44,000 volts? All else being equal, and it really isn't but it would take a thickness 0.091" for polyester tape to withstand 44.000 volts.

I'm not at all suggesting in any way that it would be safe to throw a 1/2" polyester rope over a 44,000 volt line, there are other considerations as well. But I would not expect any current to flow just from a 1/2" polyester rope being in contact with a 44,000 volt line. Now it could be that in the manufacture of polyester rope per se, that the dielectric strength is altered dramatically some how, maybe by dyes, but it's really not known if the manufacturing process degrades the dielectric strength or not.

What I'm pointing out is, air has a dielectric strength of 76,200 volts per inch and polyester has a dielectric strength of 2,272,700 volts per inch - 30 times higher than air. This suggests, not prove, but suggests, that clean, dry polyester is 30 times better than air as an insulator.

I expect that said experienced linemen have practical experience with rope contact with live wires, I suspect it's the rope contaminants, moisture content etc. that causes them to think (or say) "What are you stoopid?" when anyone questions their opinion on rope contacting wires. In other words line clearance workers are not climbing in a lab with pristine materials (clean ropes) and perfect conditions, more likely they're in the worse possible conditions.
-Andrew

Ok, rephrasing a bit:

Tom introduced the notion of a clean, dry rope, albeit in a hypothetical context: "...what they think of the mythical 'clean, dry rope'". He also brought up the question of whether a non-conductor was an insulator or not. So, I explained why a clean, dry polyester rope, was an excellent insulator. But no one is suggesting, approving, or condoning a rope coming in contact with an energized HV line.

Considering contaminants suggests that the rope is uniformly, and completely contaminated for the full length of the rope, and the contaminants lower the dielectric strength of the rope by a factor of say 100 - that'd still be a dielectric strength 22,727 volts per inch of rope, even by a 1000 would be 2,272 volts per inch of rope, AND we think there's a possiblity of this rope coming in contact with an HV electrical line.....

Who's gonna do that? When's that ever been the subject? The subject of the thread is how close a tree can be to a powerline, not how dry or contaminated my rope can be and contact a power line.

But to address the local issue, polyester is an excellent insulator.

I have a sample of an insulated/dielectric rope from a manufacturer. If a climber looks at it they would see a Tenex looking rope with a stiff orange coating. The rope is designed to pull energized lines onto towers when they are rebuilding. When I got the sample I had a theoretical discussion with the rep. I asked if one of the strands of the rope could be used as the mythical 'clean, dry rope'. My thought was to make a vacuum pack with a throwline on either end to be opened in case of an emergency contact. He knew where I was going and talked with confidentiality. He explained that this could be done but the company would never do it because of liability reasons. We looked at the test specifications for the rope. That was an interesting discussion.

The leading cause of deaths for arborists is electrocution. That's why there are strick minimum approach distances for anyone working around lines.

As always, I really appreciate Ron's insights. Even though rope is likely to be a better insulator than even air I'm still not getting near the lines